diff --git a/platform/lang-impl/src/com/intellij/refactoring/changeSignature/ChangeSignatureGestureDetector.java b/platform/lang-impl/src/com/intellij/refactoring/changeSignature/ChangeSignatureGestureDetector.java
index 784dfc9fa111..6bb1e6e798b9 100644
--- a/platform/lang-impl/src/com/intellij/refactoring/changeSignature/ChangeSignatureGestureDetector.java
+++ b/platform/lang-impl/src/com/intellij/refactoring/changeSignature/ChangeSignatureGestureDetector.java
@@ -101,8 +101,7 @@ public class ChangeSignatureGestureDetector extends PsiTreeChangeAdapter impleme
     final MyDocumentChangeAdapter adapter = myListenerMap.get(element.getContainingFile());
     if (adapter != null && adapter.getCurrentInfo() != null) {
       final LanguageChangeSignatureDetector detector = LanguageChangeSignatureDetectors.INSTANCE.forLanguage(element.getLanguage());
-      LOG.assertTrue(detector != null);
-      return detector.isChangeSignatureAvailable(element, adapter.getCurrentInfo());
+      return detector != null && detector.isChangeSignatureAvailable(element, adapter.getCurrentInfo());
     }
     return false;
   }
@@ -112,9 +111,8 @@ public class ChangeSignatureGestureDetector extends PsiTreeChangeAdapter impleme
     final MyDocumentChangeAdapter adapter = myListenerMap.get(element.getContainingFile());
     if (adapter != null && adapter.getCurrentInfo() != null) {
       final LanguageChangeSignatureDetector detector = LanguageChangeSignatureDetectors.INSTANCE.forLanguage(element.getLanguage());
-      LOG.assertTrue(detector != null);
       final ChangeInfo currentInfo = adapter.getCurrentInfo();
-      if (detector.isChangeSignatureAvailable(element, currentInfo)) {
+      if (detector != null && detector.isChangeSignatureAvailable(element, currentInfo)) {
         return currentInfo instanceof RenameChangeInfo ? ChangeSignatureDetectorAction.NEW_NAME
                                                        : ChangeSignatureDetectorAction.CHANGE_SIGNATURE;
       }